Ex wife found out

My ex wife of 6yrs (we have two kids together) has just found out I was sleeping with men the whole time I was with her. I treated this woman so bad guys and every time she wanted to end things I convinced her to stay with me. I loved her but I was sexually attracted to men. I prefer men but also wanted her as she was that type of woman that everyone wanted to have and was very hard to get. This turned me on. It turned me on more knowing that she didn't know. I feel bad about the things I've said and done to her and the whole thing is a mess. But I'm so worried she is going to expose me and I honestly have no fucking clue what to do. I actually want to contact her to explain and apologise but know that will make it worse. What the fuck do I do? I don't even know exactly what she knows just that she knows as she messaged me brother and told him that I was gay. I've been on videos on other sites and am going nuts thinking about what she knows. I know I'm a piece of shit but there are a lot like me. What the fuck do I do??